[Go] Fix ArrayData staticcheck nil check

[zeroshade]

Describe the bug, including details regarding any error messages, version, and platform.

Go CI's are currently throwing a staticcheck issue with the following error text:

arrow/array/data.go:209:29: this comparison is always true (SA4023)
	arrow/array/data.go:209:13: the lhs of the comparison is the 1st return value of this function call
	arrow/array/data.go:179:16: (*github.com/apache/arrow/go/v15/arrow/array.Data).Dictionary never returns a nil interface value

Looking at the code it should just use d.dictionary directly rather than calling d.Dictionary()

Component(s)

Go